Continuous extrusion apparatus

ABSTRACT

Continuous extrusion apparatus (FIG. 1) including a rotatable, grooved, wheel 2 is provided with a shoe 6 mounted on a pivot 7 to be rotatable between a position engaging the wheel 2 and a dis-engaged position. The shoe 6 carries a tooling cartridge 10 including an abutment block 14, an expansion block 16, a die block 18 and an exit block 20 connected together with bolts 22 and held in position by locking keys 46 and a retaining ring 50. A reciprocable ram 60 registers with the cartridge 10 when the shoe 6 is in the dis-engaged position and is operable to raise a cartridge 10 from an associated heating chamber 56 into the shoe 6 or to lower a cartridge 10 from the shoe 6 into a storage chamber (not shown). By utilizing a cartridge 10, change-over and pre-heating of sets of dies is facilitated, enabling the apparatus to be connected directly to a continuous casting furnace (not shown).

DESCRIPTION

This invention relates to apparatus for the forming of metals by acontinuous extrusion process in which feed stock is introduced into acircumferential groove in a rotating wheel to pass into a passagewayformed between the groove and arcuate tooling extending into the groove.The tooling includes an aperture formed in a shoe portion and extendingin a generally radial direction from the groove to a die and an abutmentis provided to constrain the feedstock to flow through the aperture andthe die.

In GB-A-0125788 there is described continuous extrusion apparatusincluding a rotatable wheel having a plurality of spaced apartcircumferential grooves, and provided with arcuate tooling with a shoeportion bounding radially outer portions of the respective groovesformed with exit apertures extending in a generally radial directionfrom the respective grooves to a chamber and abutments displaced in thedirection of rotation of the wheel from the apertures extending into thegrooves, the chamber discharging to a die orifice.

In a continuous extrusion apparatus of the form set out, according toone aspect of the invention the tooling includes an entry blockpositioned in a recess in the shoe portion bounding the grooves togetherwith an abutment block, an expansion block, a die block and an exitblock, the abutment block, expansion block and exit block being seriallypositioned in a stepped bore in the shoe portion with the abutment blockseating upon a shoulder in the bore adjacent the entry block and meansbeing provided to secure the exit block axially of the bore.

Preferably, the abutment block extends through an aperture in the entryblock of generally frusto-conical form and flat faces formed onabutting, otherwise frusto-conical, faces co-act angularly to locate theabutment block relative to the entry block.

Desirably, a divergent expansion chamber extending through the expansionblock includes an initial section and an outlet section each offrusto-conical form with the outlet section having a greater cone anglethan the cone angle of the initial section.

Suitably, the means securing the exit block axially of the bore includelocking keys moveable between an engaged position effecting secural anda disengaged position allowing removal of the exit block. Additionally,a retaining ring may be threaded into an end of the bore remote from thewheel to bear against the locking keys in an engaged position.

In another embodiment of the invention, the abutment block, theexpansion block, the die block and the exit block are disconnectablysecured together to form a tooling cartridge removable from andinsertable into the bore as a whole and a heating chamber is providedadapted to effect heating of the tooling cartridge prior to insertioninto the bore.

Advantageously, the tooling cartridge is insertable into and removablefrom the bore by actuation of a reciprocable ram aligned with the bore.

In a further embodiment of the invention, a continuous casting furnaceis arranged to discharge cast feedstock direct to the circumferentialgrooves.

Suitably, the cast feedstock is discharged through a tunnel from thecontinuous casting furnace to the circumferential grooves. The tunnelmay be lined with heat insulating material and may be arranged to besupplied with gases having little or no oxygen content.

The invention will now be described, by way of example, with referenceto the accompanying, partly diagrammatic drawings, in which:

FIG. 1 is a cross-sectional side elevation of a continuous extrusionapparatus, indicating a shoe and associated tooling in a positiondis-engaged from a rotatable, grooved, wheel, the engaged position beingindicated in chain dotted outline, together with an associated heatingchamber and a portion of a ram;

FIG. 2 is a plan view taken in the direction of the arrow II on FIG. 1:

FIG. 3 is a cross-section taken on the line III--III of FIG. 1; and

FIG. 4 is a cross-section taken on the line IV--IV of FIG. 1.

As shown in the accompanying drawings, a wheel 2 of a continuousextrusion machine is formed with a pair of axially spacedcircumferential grooves 4. A shoe 6 mounted on a pivot 7 and rotatableto co-act with the wheel is formed with a stepped bore 8 into which atooling cartridge 10 is inserted to seat on a shoulder 12. The toolingcartridge 10 includes an abutment block 14, an expansion block 16, a dieblock 18 and an exit block 20 connected together by bolts 22 threadedinto the abutment block 14. A recess 24 in the shoe 6 registering withthe bore 8 carries an entry block 26 mating with the abutment block 14and is retained in position by a spring loaded clamp 28. Flat faces (notshown) on the entry block 26 and the abutment block 14 co-act angularlyto locate the blocks the one relative to the other. The expansion block16 is penetrated by a divergent expansion chamber 30 registering withentry passages 32 of frusto-conical form in the abutment block, aninitial portion of the expansion chamber 30 having a frusto-conical wall34 of the same cone angle as that of the entry passages 32, the form ofthe entry passages being modified to merge smoothly together and intothe expansion chamber 30. An outlet portion of the expansion chamber isformed with a frusto-conical wall 36, of slightly greater cone anglethan that of the wall 34, and a short cylindrical wall 38 at the outlet.To accommodate the divergent form of the expansion chamber 30, theexpansion block 16 is of stepped outer diameter having a step 40, with acorresponding step 42 being provided in the bore 8 but spaced axiallyfrom the step 40 to ensure that the tooling cartridge 10 seats only onthe shoulder 12.

The shoe 6 is formed with a pair of slots 44, intersecting with the bore8 and is provided with radial locking keys 46 which, in an insertedposition, bear against an outer face 48 of the exit block 20. Aretaining ring 50 is threaded into a counter-bore 52 to bear against thelocking keys 46 such that, upon tightening the retaining ring againstthe locking keys, the tooling cartridge 10 is urged to seat firmly uponthe shoulder 12.

A sliding unit 54 is positioned below the shoe 6 in register with thebore 8 and includes a heating chamber 56 and a storage chamber 58 fortooling cartridges 10. A hydraulic ram 60 positioned co-axially of thebore 8 is actuable to move the tooling cartridges 10 between the slidingunit 54 and the bore 8, the retaining ring 50 being slacked-off and thelocking keys 46 withdrawn to permit passage of the tooling cartridge.

To assembly a tooling cartridge 10 into the bore 8 in the shoe 6,appropriate sizes and forms of the abutment block 14, expansion block16, die block 18 and exit block 20 are selected and secured together bythe bolts 22, abutting dished and stepped end faces facilitating theoperation and formation of a sealed junction. The assembled toolingcartridge 10 is then placed in a heating chamber 56 and heated to raisethe temperature of the cartridge to a temperature approximating toworking temperature. Upon the cartridge 10 reaching the requisitetemperature, the hydraulic ram 60 is actuated to raise the cartridgeinto the bore 8 and to engage the flat faces on the abutment block 14with the corresponding faces on the entry block 26 previously positionedin the recess 24 of the shoe 6. The radial locking keys 46 are thenmoved to the inserted position, the hydraulic ram retracted and theretaining ring 50 tightened onto the locking keys 46. The shoe 6 is thenswung on the pivot 7 into engagement with the wheel 2 (as indicated inbroken outline) whereupon, upon feedstock being fed to the groove 4 andthe wheel driven, continuous extrusion may be commenced with a minimumof wastage.

To substitute a different die, the machine is stopped and the shoe swungto the open position shown in FIG. 1. The retaining ring 50 is thenslacked off, the storage chamber 58 of the sliding unit 54 aligned withthe bore 8, the hydraulic ram 60 actuated to engage the exit block andthe locking keys 46 moved to a withdrawn position. The hydraulic ram 60is then actuated to lower the tooling cartridge 10 into the storagechamber 58, the sliding unit indexed along to bring the replacementtooling cartridge 10, preheated to the operating temperature of thewheel 2 in the heating chamber 56, into alignment with the bore 8whereupon the hydraulic ram is actuated to position the replacementtooling cartridge in the bore 8 as previously described with a minimalloss of down-time.

Such an arrangement lends itself to deriving feedstock from a continuouscasting furnace since die changes may be effected rapidly and, since thedie and associated tooling are pre-heated, little time need be lost inre-commencing extrusion, so that the build-up in molten feedstock may beaccommodated in the continuous casting furnace. By casting feedstockfrom a continuous casting furnace and feeding over a shortest possibledistance, through a tunnel having a wall of insulation material toreduce heat losses, direct to the continuous extrusion apparatus, theheat stored in the feedstock immediately following solidification isconserved and surface oxidation minimised. In situations where it isdesired to avoid surface oxidation, output from the continuous castingfurnace is fed through a tunnel of gases of reduced, or substantiallyno, oxygen content.

It will be appreciated that whilst a die for extruding a solid stripproduct has been illustrated, a full range of die producing solid orhollow products may be utilised.

We claim:
 1. Continuous extrusion apparatus, comprising:a) a rotatablewheel having a plurality of spaced apart circumferential grooves; b)arcuate tooling with a shoe portion bounding radially outer portions ofthe respective grooves formed with exit apertures extending in agenerally radial direction from the respective grooves to a chamber; c)abutments displaced in the direction of rotation of the wheel from theapertures extending into the grooves, the chamber discharging to a dieorifice; d) the tooling comprising an entry block positioned in a recessin the shoe portion bounding the grooves, an abutment block, anexpansion block, a die block and an exit block; e) the abutment block,expansion block, die block and exit block are serially positioned in astepped bore in the shoe portion; f) the abutment block engaging upon ashoulder in the bore adjacent the entry block; g) means for securing theexit block axially of the bore; h) the abutment block extending throughan aperture in the entry block of generally frusto-conical form; i) flatfaces formed on abutting faces of the abutment block and the entry blockco-acting angularly to locate the abutment block relative to the entryblock; j) the abutment block, the expansion block, the die block and theexit block are disconnectably secured together to form a toolingcartridge; k) a heating chamber and a storage chamber each arranged toaccommodate the tooling cartridge are movably positioned to be indexedalternately into register with the bore at an open position of the shoe;l) a support ram is reciprocable through the respective heating orstorage chamber when indexed into registration with the bore to effectsupport of the tooling cartridge; m) the tooling cartridge is removablefrom and insertable into the bore as a whole supported on the supportram; and n) the heating chamber is adapted to effect heating of thetooling cartridge prior to insertion into the bore.
 2. Continuousextrusion apparatus as claimed in claim 1, characterised in that adivergent expansion chamber (30) extending through the expansion block(16) includes an initial section and an outlet section (36) each offrusto-conical form with the outlet section (36) having a greater coneangle than the cone angle of the initial section (34).
 3. Continuousextrusion apparatus as claimed in claim 1, characterised in that themeans securing the exit block axially of the bore include locking keys(46) moveable between an engaged position effecting secural and adisengaged position allowing removal of the exit block (20). 4.Continuous extrusion apparatus as claimed in claim 3, characterised inthat a retaining ring (50) is threaded into an end of the bore (8)remote from the wheel (2) to bear against the locking keys (46) in anengaged position.
 5. Continuous extrusion apparatus as claimed in claim1, characterised in that a continuous casting furnace is arranged todischarge cast feedstock direct to the circumferential grooves (4). 6.Continuous extrusion apparatus as claimed in claim 5, characterised inthat the cast feedstock is discharged through a tunnel from thecontinuous casting furnace to the circumferential grooves (4). 7.Continuous extrusion apparatus as claimed in claim 6, characterised inthat the tunnel is lined with heat insulating material and is arrangedto be supplied with gases having little or no oxygen content.